1. Field
This disclosure relates generally to semiconductors, and more specifically, to the control of a supply voltage used by semiconductors.
2. Related Art
Integrated circuits are required to efficiently use power. To reduce power consumption, some integrated circuits function in two differing power modes such as a normal power mode and a reduced power mode for idle states of operation. For example, the reduced power mode may be entered during time periods of inactivity in an effort to reduce static current leakage in digital logic circuitry.
When electronic circuits first transition from the reduced power mode to the normal power mode a certain amount of time delay exists in order to re-establish a higher operating voltage in the circuitry. In some applications state information must be restored prior to beginning normal operation. The time delay associated with leaving a reduced power mode of operation is undesirable to the user of the integrated circuit. Also, when supply voltages transition from a ground value (i.e. a first rail value) to a full value, the transition can generate current spiking in some circuitry. Some circuits reduce the supply voltage by a diode drop, which is equivalent to a transistor threshold, as opposed to removing the supply voltage during the reduced power mode of operation. However, such circuits experience variation in the voltage that is reduced as a result of variation in circuit parameters over process and temperature. As a result, the amount of power being conserved during the reduced power mode of operation significantly varies and is difficult to quantize.